1. Field of Invention
The invention relates to a device for collecting fluid-samples in circuits, e.g. in circuits for peritoneal dialysis (PD), in particular for automatic peritoneal dialysis (APD).
2. Description of the Prior Art
Peritoneal dialysis is a treatment for purifying the blood of a patient affected by renal insufficiency. Unlike conventional haemodialysis, in peritoneal dialysis the membrane used to filter the blood does not consist of an artificial element provided outside the patient's body, but consists of the peritoneum. The peritoneum is a membrane situated in the abdomen and surrounding the internal organs. Since it is thin and highly vascularized it is possible to apply the physical principle of dialysis directly inside the patient's body.
Peritoneal dialysis requires a catheter which must be introduced permanently inside the abdomen so as to allow connection of the peritoneal cavity to an external circuit. The external circuit generally comprises a bag containing pure dialysate and a drainage outlet.
The treatment of peritoneal dialysis generally comprises a first infusion phase (or fill) during which the pure dialysate is supplied via the catheter to the peritoneal cavity. During the second so-called dwell phase, during which no external operations are required, dialytic exchange between the patient's blood and the dialysate takes place. During the third and final drainage stage (or drain) the saturated dialysate is removed from the peritoneal cavity.
In order to obtain satisfactory purification of the blood, the entire treatment cycle described above must be repeated several times in succession over the course of 24 hours. In the case of APD, the various treatment cycles are performed in succession throughout the night by means of a special machine called an “automatic cycler” which automatically sets and regulates the fill, dwell and drain phases.
In order to monitor the effectiveness and quality of the peritoneal dialysis treatment, it is known to analyse samples of saturated dialysate which is discharged.
For this reason, it has proved to be extremely useful to collect the samples of used dialysate at regular intervals and automatically, i.e. without the need for any intervention either by the patient or by other assisting persons. It is in fact desirable to eliminate any need for intervention, especially during the night, otherwise one of the main advantages of this treatment method is lost.
For these reasons there exists the need to introduce into the circuit a device which autonomously performs periodic sampling of dialysate samples.
A device of this type is described in WO 99/06082. This device, however, is not without drawbacks. It is, in fact, extremely complex since it is also intended to perform other functions, such as that of the cycler itself or also the preparation of the optimum dialysate solution for the individual patient.